Flat side valve for pressure balanced power steering pump with improved aspirator action

ABSTRACT

PUMP BYPASS IS CHANNELED INTO AN ANNULUS AND THENSE INTO A SINGLE FLOW PASSAGE CONSTRUCTED TO OBTAIN MAXIMUM ASPIATION AT AN OIL MAKEUP PORT SO AS TO OBTAIN MAXIMUM INLET SUPERCHARGE.

H. M. CLARK 3,671,143 FLAT SIDE VALVE FOR PRESSURE BALANCED POWER STEERING PUMP June 20, 1972 WITH IMPROVED ASPIRATOR ACTION 2 Sheets-Sheet 1 Filed Nov. 5, 1970 INVENTOR.

; TTORNE YS H. M. CLARK 3,671,143 FLAT SIDE VALVE FOR PRESSURE BALANCED POWER STEERING PUMP June 20, 1972 WITH IMPROVED ASPIRATOR ACTION 2 Sheets-Sheet 3 Filed Nov. 5, 1970 fig. 3

fig. 5

0 97/ 776 /r, 4 a 7 4 A a I 5 B, 4 a /a 6 J, 2 2 x 4 4 0 MW 66 J 007 a a 3 7 m M 2 2 4 7 d W/ ;/\74 2 \\J\\\\..\/\\\- am \a a 6 M 6 Z fo 4 w llab riff W ATTORNEYS MW k%d/ Patented June 20, 1972 FLAT SIDE VALVE FOR PRESSURE BALANCED POWER STEERING PUMP WITH IMPROVED ASPIRATOR ACTION Hubert M. Clark, Birmingham, Mich., assignor to TRW Inc., Cleveland, Ohio Filed Nov. 5, 1970, Ser. No. 87,050 Int. Cl. F0411 49/08 US. Cl. 417-79 8 Claims ABSTRACT OF THE DISCLOSURE Pump bypass is channeled into an annulus and thence into a single flow passage constructed to obtain maximum aspiration at an oil makeup port so as to obtain maximum inlet supercharge.

BACKGROUND OF THE INVENTION The field of the invention This invention relates generally to pressure balanced power steering pumps of the type having a housing and a stackup of parts including a so-called cam rings forming a pumping chamber, in a rotor carrying one or more slippers which are free to move radially and rock angularly in following the adjoining contour of the pumping chamber wall. More specifically, the following invention relates to an improved valve plate and upper plate provided in such a pump whereby maximum aspiration is achieved to obtain maximum inlet supercharge.

The prior art The prior art is exemplified by a copending application Ser. No. 44,268 filed June 8, 1970 assigned to the same assignee as the present application, that application discloses the concept of a so-called flat side valve in a pressure balanced power steering pump. The pump construction includes many parts and general organization which have been in widespread use, namely, the cam ring which has a contoured bore forming a pumping chamber, a notched rotor rotatable Within the cam ring and including a plurality of slippers or pumping elements which are free to move radially in the notched rotor and to rock angularly in following the adjacent bore wall of the pumping chamber. Such construction also includes slipper springs for initially biasing the slippers or pumping elements outwardly against the bore wall, a housing for supporting a shaft by means of which the pump is driven from a suitable power source connection and the usual shaft seal and shaft bushing.

SUMMARY OF THE INVENTION The pump of the present invention utilizes a shell somewhat similar to the prior art pump, but shorter. An outlet fitting is welded into the shell and is constructed to serve as a guide for a valve plate. The valve plate of the present invention has a flat lower surface, a bore to accept a guide on the outlet fitting and a relief valve arrangement comprising a seat, a ball, a spring and an adjustable plug.

An upper plate is constructed of powdered metal by briqueting or pressing two separate parts, assembling the two parts and then sintering or fusing them together. By virtue of that manufacturing technique, a series of passages may be formed in the upper plate without any machining operations, although it will be understood that the upper plate could be constructed by other fabricating techniques such as the common casting-coring procedures.

The passages formed in the upper plate include pump discharge or outlet passages so that oil flows from the pump through the outlet ports, through the outlet passages and into a centrally disposed chamber in the one portion of the upper plate adjacent the valve plate.

Two inlet ports are also formed in the upper plate so that oil flows from the area around the cam through the inlet passages and then into the interior of the pump.

The upper plate is further characterized by a bypass port and a makeup port. The upper and lower sections of the upper plate are so formed that oil flows from the bypass annulus and then into the bypass port and then flows by the makeup port in such a manner as to cause an aspirator elfect, drawing oil from the makeup port and thus supercharging the oil into the area around the cam and at the pump inlet ports.

The top side of the upper section of the plate is constructed with an inner land surrounding the central bore and an outer land around the outer diameter of the upper plate.

A bypass annulus is formed between such lands. The inner land seals against the adjoining surface of the valve plate until the oil flow through an orifice leading from the centrally disposed bore into a chamber in the valve plate becomes suflicient to create enough pressure drop so that the valve plate is raised against the force of a flow spring to bypass oil from the centrally disposed bore into the bypass annulus and then into the bypass and makeup passage.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a pressure balanced power steering pump provided in accordance with the principles of the present invention and the section is taken on line II of FIG. 2.

FIG. 2 is a cross-sectional view taken on line IIII of FIG. 1 and shows additional details of the upper plate construction.

FIG. 3 is a composite cross-sectional view, the righthand portion of FIG. 3 being taken on line III R--III R of FIG. 2 and the lefthand portion of FIG. 3 being taken on line III LIII L of FIG. 2.

FIG. 4 is a fragmentary cross-sectional view taken on line IVIV of FIG. 2.

FIG. 5 is a fragmentary cross-sectional view showing an alternative construction.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Although the principles of the present invention are of general applicability, a particularly useful construction in which the inventive principles may be embodied constitutes a pressure balanced power steering pump shown generally in FIG. 1 at 10. The pump 10 has a housing 11 in which is formed a bore 12. A bearing sleeve 13 in the bore 12 journals a shaft 14 which may be connected to a suitable power source such as the motive system of an automobile. A shaft seal is shown at 16 and the housing has a radially outwardly extending portion 17 adapted to cooperate wth a reservoir which may be clamped to the outer circumferentially extending wall 18 of the housing 11.

The shaft 14 has a coupling portion 19 which is splined to the rotor 20 of a rotatable fluid displacement means.

3 at 21 of a pumping chamber provided by a so-called cam ring 22.

The parts of the pump are stacked up in an axial row to form a cartridge enclosed within a shell shown generally at 32. Bolts 24 and 26 clamp upper plate 60, cam ring 22 and bottom plate 160 onto housing 11 as at 27. There are four bolts holding the shell to the housing, one of which is shown at 25 on FIG. 1.

In accordance with the principles of the present invention, the shell member 23 is generally similar in structural configuration to that provided heretofore, however, it is somewhat shorter in length. Thus, the shell member is generally cup-shaped in configuration and has an end wall 28 as well as sidewalls 29 terminating in a radially outwardly extending flange 30.

An outlet fitting is shown generally at 31 and has an externally threaded nipple 32 by means of which the outlet fitting 31 may be connected in the conduit system leading to a point of utilization. The outlet fitting 31 extends through an opening 33 formed in the wall 28 of the shell 23 and is firmly fastened to the shell 23 as by means of a welded joint 34.

The hollow interior of the shell 23 is shown at 36. Extending into the hollow interior 36 is a cylindrical boss 37 formed on the outlet fitting 31 which is constructed to serve as a guide for a valve plate shown generally at 40. The peripheral wall of the cylindrical boss 37 is recessed as at 38 to receive an O-ring seal 39. Extending axially through the outlet fitting 31 is a bore 41 forming a discharge passage and which is counterbored as at 42, thereby forming a shoulder 43 against which one end of a coil spring 44 may be bottomed.

The valve plate 40 is a generally disc-shaped member having a flat low valving surface 46. The valve plate 40- has an enlarged boss portion within which is formed a discharge chamber shown at A bounded by a cylindrical wall 47 which slidingly receives the cylindrical portion 37 of the outlet fitting 31. The bottom wall of the chamber A shown at 48 bottoms the other end of the spring 44, thereby preloading the valve plate 40 in an axial direction away from the outlet fitting 31.

The valving surface 46 is centrally recessed as at 49 and a flow orifice is formed at 50 through which fluid at pump-generated pressure is directed into the chamber A and from thence into the passage 41 for transmission to a point of utilization.

The valve plate 40 also contains a relief valve arrangement. First of all, there is formed a radially outwardly extending passage 51 which intersects the wall 47 thereby to communicate with the chamber A. The passage 11 is successively counterbored first of all to receive a seat forming member 52 providing a valve seat for a ball 53 spring loaded by a coil spring 54, the other end of which is bottomed against an adjustable plug 56. The relief valve adjustment plug 56 is a drawn cup with threads rolled on the outside diameter. Further, there is formed in the end wall thereof a hex hole 57 which is adapted to cooperate with a hex wrench for axial adjustment, thereby to permit selective adjustment of the relief valve.

A relief valve opening 58 is formed in the shell 23 immediately adjacent the relief valve, thereby to vent the fluid back into the reservoir surrounding the shell 23.

The upper plate of the present invention is shown generally at 60 and comprises two separate parts including an upper section 61 and a lower section 62. Although the upper plate 60 can be constructed by any common castingcoring method, it is specifically contemplated by the present invention that the upper plate be constructed of powdered metal by briqueting or pressing the two separate parts 61 and 62, whereupon the parts are assembled and then sintered or fused together at a bonding joint 63. By so constructing the upper plate 60, a series of passages may be formed therein without any separate machining operations.

With respect to the passages that are formed in the upper plate 60, the section of FIG. 2 which is taken through the lower section 62 shows two outlet ports 64 and 66 respectively. The righthand section of FIG. 3 is through one of the outlet ports 66 and it will be understood that the other is identical. The passage 66 and 64 brings the oil discharged from the bottom of the rotor into ports in the lower plate into passage 67. The oil discharge from the top of the rotor flows directly into passage 67 as indicated on FIG. 3. In a slipper-type pump, and in order to assist in venting the notches behind the slippers at the discharge portion of the pump, auxiliary discharge passages are shown at 67a.

The cross section of FIG. 2 also shows two peripheral inlet ports 68 and 69. The lefthand section of FIG. 3 is through one of the inlet ports 69 and it will be understood that the other is identical. As shown on the draw ings, all of the fluid in the area around the cam ring 22 enters an inlet port 69 and into the interior of the pump for filling the working chamber between an adjoining pair of slippers. To assist in filling all of the space, a passage 70 communicates with an auxiliary inlet passage 69a located radially inwardly of the main inlet ports 68 and 69 thereby to further assist in filling the inlet areas.

Referring further to FIG. 2, there is shown a bypass port 71 and a makeup port 72 formed in the shell 23.

The section of FIG. 4 is through the bypass port 71 and it will be noted that the upper plate 60 is formed with a makeup passage 73 which is angled in such a manner as provide a mouth portion in register with the makeup port 72 and which intersects the bypass port 71, which extends upwardly and inwardly relative to the upper plate 60.

The top side of the upper section 61 of the upper plate 60 is constructed with an inner land 76 surrounding the chamber B and an outer land 77 located at the outer diameter of the upper plate 60. A relief 78 is provided in the valve plate 40 to clear the land 77. A bypass annulus 79 is formed in the upper section 61 between the lands 76 and 77 As shown in FIG. 4, the makeup port 71 constitutes a single passage intersecting the bypass annulus 79. Accordingly, the upper and lower sections 61 and 62 of the upper plate 60 are so formed that fluid flows from the bypass annulus 79 and then into the bypass port 71, and thence, will flow past or by the makeup port and makeup passage 72, 73 thereby causing an aspirator effect, drawing fluid from the makeup port 72, and, thus, supercharging the fluid in the area around the cam 22 and, thus, at the pump inlet ports 68 and 69.

The inner land 76 seals against the valving surface 46 of the valve plate 40 until the fluid flow through the orifice 50 from the chamber B into the chamber A becomes suflicient to create enough pressure drop so that the valve plate 40 is raised against the force of the flow spring 44, thus bypassing fluid from the chamber B into the bypass annulus 79, thence into the bypass port 71 and the makeup passage 73 as referred to.

In FIG. 5, an alternate construction is shown which is generally similar to the arrangement already described except that a sheet metal shield 80 is pressed onto the valve plate and surrounds the upper plate to help contain the fluid in the bypass annulus, thereby to further aid and assist the aspirator effect and the supercharging action, Like reference numerals with the suffix a are used to identify corresponding parts. It will be noted that the outer periphery of the upper section 61a is relieved on its outer periphery to accommodate the shield 80.

It may be further noted that the outer land 77 on the upper plate 60 besides providing a boundary for the bypass annulus 79 also supports the part when the top surface is ground and/ or lapped to obtain maximum flatness on the inner land '76.

While minor modifications might be suggested by those versed in the art, it should be understood that I wish to obtain within the scope of the patent warranted hereon all such modifications as reasonably and properly come within the scope of my contribution to the art.

I claim as my invention:

1. In a pressure balanced power steering pump of the type having a housing, cam, rotor, slipper and shaft, the improvement of l a shell of generally cup-shaped configuration cooperating with said housing to enclose the parts of the P p an outlet fitting in said shell through which all of the fluid pumped is directed to a point of utilization,

said outlet fitting having a cylindrical portion pro- [iecting inwardly of said shell, and a valve plate having a bore formed therein, said cylindrical portion of said outlet fitting receiving said valve plate bore for guiding axial movement of said valve plate,

said valve plate and said outlet fitting together with one another forming a chamber inwardly of said cylindrical portion for receiving pressurized fluid from the pump, whereby upon rotation of the shaft in the housing the rotor will turn and the slipper will operate in the cam to pressurize fluid for discharge to said chamber.

2. In a pressure balanced power steering pump as defined in claim 1,

said valve plate having formed therein a passage means extending radially outwardly from said chamber and means in said passage means comprising a seat, a ball, a spring and an adjustable plug forming a relief valve for venting excess pressure in said chamber to a zone of reduced pressure.

3. In a pressure balanced power steering pump of the type having a housing, cam, rotor, slipper and shaft, the improvement of means including a valve plate forming a chamber for receiving pressurized fluid from the pump,

said valve plate having a flat valving surface, and an upper plate comprising first and second parts which together with one another form a series of passageways including outlet passages in said first part receiving fluid at pump-generated pressure and directing the pressurized fluid to a central bore in said second part disposed opposite said flat surface of said valve plate,

said second part of said upper plate having formed adjacent said flat valving surface an inner land surrounding said central bore, an outer land around its outside diameter, and a bypass annulus between said lands, said valve plate having an orifice formed therein between said central bore in said chamber,

biasing means preloading said valve plate towards said upper plate, said inner lands sealing against the valve plate valving surface until flow through said orifice from said bore into said chamber becomes suflicient to increase the pressure drop so that the valve plate is moved against the biasing means, thereby bypassing fluid into the bypass annulus,

said upper plate having inlet passages formed therein through which fluid flows from an area circumiacent the cam of the pump into the pump,

said upper plate having a bypass port and makeup port.

formed therein disposed with respect to one another so that the fluid flows from the bypass annulus into the bypass port and past the makeup port, thereby causing an aspirator effect drawing fluid from the makeup port and supercharging the area around the cam at the inlet ports.

4. In a pressure balanced power steering pump of the type using a stackup of parts including a valve plate and a cam ring forming a pumping chamber, the improvement of an upper plate comprising two separate parts fused together and having formed therein a centrally disposed bore,

an inner land surrounding said bore, an outer land at the outer diameter of said upper plate, and an annulus between said lands,

and bypass passage means in said upper plate for conducting pressurized fluid from said annulus to the pump inlet whereby fluid at pumpgenerated pressure supplied to said bore is selectively bypassed to said annulus whenever said inner land is separated from an adjoining surface of the valve plate.

5. In a pressure balanced power steering pump of the type using a stackup of parts including a valve plate and a cam ring forming a pumping chamber, the improvement of an upper plate comprising two separate parts fused together and having formed therein a centrally disposed bore, an inner land surrounding said bore, and an annulus outwardly circumjacent said land, enclosure means outwardly circum-jacent said annulus to help contain fluid in the annulus,

and bypass passage means in said upper plate for conducting pressurized fluid to the pump inlet, whereby fluid at pump-generated pressure supplied to said bore is selectively bypassed to said annulus whenever said inner land is separated from an adjoining surface of the valve plate.

6. In a pressure balanced power steering pump of the type defined in claim -5 and further characterized by said enclosure means comprising an outer land at the outer diameter of said upper plate providing a peripheral boundary for said annulus, and said outer land also providing a support surface for supporting said upper plate, said top surface of said upper plate being finished to obtain maximum flatness on said inner land surrounding said bore.

7. In a pressure balanced power steering pump of the type described in claim 5, said enclosure means comprismg a circumferentially continuous shield connected to said valve plate and surrounding the upper plate to help 50 contain the fluid in the annulus.

8'. In a pressure balanced power steering pump of the type defined in claim 5, said bypass passage means comprising a bypass port and a makeup port disposed in said upper plate so that fluid flows from the annulus into 55 the bypass port and past the makeup port to cause an aspirator effect drawing fluid from the makeup port and supercharging the inlet area of the pump.

References Cited UNITED STATES PATENTS 3,200,752 8/1965 Clark et a1. 417-300 3,388,670 6/1968 Connelly 417188 3,125,028 3/1964 Rohde 417-30O 2,380,783 7/ 1945 Painter 4l7--310 CORNELIUS J. HUSAR, Primary Examiner R. I. SHER, Assistant Examiner US. Cl. X.R. 

